Conventionally, for example, as disclosed in Japanese Laid-Open Patent Publication No. 2004-118383 (JP2004-118383A), a virtual switch providing device has been proposed as an electronic device for increasing or decreasing volume by a volume switch that is disposed on a touch panel type display unit.
With the virtual switch providing device disclosed in JP2004-118383A, as shown in FIGS. 4 and 5 thereof, a small circle, in which an indicator is arranged in one location on the circumference, is displayed in a display unit as a volume switch. When the indicator is touched by a finger on the small circle, while a positional relationship between the touch position and the indicator is maintained, the small circle is enlarged into a large circle, and an operation enabling range for the volume is displayed on the circumference of the large circle.
In JP2004-118383A, for setting a desired volume position, a technique is disclosed in which a selection can be made to subject the indicator to a slide operation (a movement operation of the touched position) along the operation enabling range on the circumference of the large circle, while touching the indicator of the large circle to thereby set a desired volume position, or to cancel touching of the indicator and set a desired volume position (touched position) instantaneously by touching a desired location within the operation enabling range on the circumference of the large circle. It is disclosed that the virtual switch providing device may be applied to an aircraft simulator.
As another conventional technology, although the disclosure thereof is not directly related to the present invention, there can be cited Japanese Laid-Open Patent Publication No. 2008-146429 (JP2008-146429A) as an electronic device equipped with a touch panel type display unit. According to JP2008-146429A, as shown in FIGS. 3, 4, 6, and 7 thereof, five selectable items, i.e., “menu”, “backlight correction”, “iris adjustment”, “effect”, and “back”, are displayed in vertical alignment on an EVF (electronic view finder), and an upper side selection area and a lower side selection area are provided respectively on upper and lower sides of an external touch panel that supports blind-touch operation. Furthermore, a blank area is disposed between the upper side selection area and the lower side selection area.
With the technique according to JP2008-146429A, for example, a digital video camera is proposed, which is configured such that, at a time that the “menu” item in the uppermost position on the EVF is selected, and when the lower side selection area of the external touch panel is touched, the item “backlit correction”, which is one item lower than the “menu” item, is selected. Along therewith, the blank area is incorporated into the lower side selection area, and that portion is controlled so as to enlarge the lower side selection area. Thus, operation mistakes are reduced, in the case that selection of the item “iris adjustment”, which is the next lower item, is to be carried out by a blind-touch operation on the touch panel.